We are considering a PostgreSQL jobs table consumed by three workers. Use https://www.postgresql.org/docs/current/sql-select.html to compare FOR UPDATE SKIP LOCKED with a normal SELECT for claiming jobs. Produce a decision table plus a transaction outline. Explain the inconsistent-view caveat, why queue-like use differs from general-purpose reads, and which crash/idempotency questions the SELECT documentation does not resolve.
10/4/2026, 11:46:45 PM · llm:deepseek:deepseek-v4-flash + heuristic (fallback from llm:cloudflare:@cf/meta/llama-3.3-70b-instruct-fp8-fast) (fallback from llm:mimo:mimo-v2.5) on 1 step
> ⚠ Low confidence — Only source excerpts are delivered; complete synthesis and per-assertion support remain unverified. Evidence assessment: the final assessment does not establish a complete supported answer for every requested part within budget. Treat this as provisional.
Source excerpts only. The draft is withheld as a conclusion; complete synthesis is unverified. Qualifying source excerpts are quoted below. Research targets are topics to investigate, not established conclusions.
Research target 1
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming rows compared with a normal SELECT?”
- “FOR UPDATE waits when another transaction already owns the row lock.” - “Add SKIP LOCKED, and PostgreSQL omits rows that cannot be locked immediately.” - “Several workers can therefore claim different jobs without coordinating through application code.”
Research target 2
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, what inconsistent-view caveat applies to FOR UPDATE SKIP LOCKED or to locking clauses in SELECT?”
- “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” - “The result is intentionally inconsistent.” - “PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.”
Research target 3
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads?”
- “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” - “PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.”
Research target 4
Requested topic (unverified): “Which crash and idempotency questions for claiming jobs with FOR UPDATE SKIP LOCKED versus a normal SELECT are not resolved by https://www.postgresql.org/docs/current/sql-select.html?”
- “A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.” - “The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.” - “This is the important turn: claiming exactly once is not the same as producing a side effect exactly once.” - “Make completion updates conditional on the current owner when stale workers must not overwrite a rescued job.”
Excerpts establish source grounding, not factual truth, entailment or whole-paper coverage. Support and coverage are estimates, not certification of a complete answer. Source statements may be wrong or conflicting. Draft conclusions are withheld; inspect the original text and obtain further review. Payment states remain in the separate receipt.
Next steps to complete this research
These are suggested follow-up steps; this run has not performed them. They do not change the recorded evidence or payment state.
- “Building a PostgreSQL Job Queue with FOR UPDATE SKIP LOCKED Akshay Gupta”: HTML text extraction failed. Look for a publisher-provided text/PDF edition of the same document and version; a preview cannot replace the original content.
- “PostgreSQL Job Queues with SKIP LOCKED CodeNotes”: HTML text extraction failed. Look for a publisher-provided text/PDF edition of the same document and version; a preview cannot replace the original content.
Evidence ledger — recorded source excerpts
Research targets are unverified topics. Coverage is an estimate of excerpt support, not proof of entailment, factual truth or a complete answer.
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming rows compared with a normal SELECT?”
80% estimated“FOR UPDATE waits when another transaction already owns the row lock.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
“Add SKIP LOCKED, and PostgreSQL omits rows that cannot be locked immediately.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
“Several workers can therefore claim different jobs without coordinating through application code.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, what inconsistent-view caveat applies to FOR UPDATE SKIP LOCKED or to locking clauses in SELECT?”
80% estimated“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“The result is intentionally inconsistent.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
“PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads?”
70% estimated“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
Requested topic (unverified): “Which crash and idempotency questions for claiming jobs with FOR UPDATE SKIP LOCKED versus a normal SELECT are not resolved by https://www.postgresql.org/docs/current/sql-select.html?”
50% estimated“A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“This is the important turn: claiming exactly once is not the same as producing a side effect exactly once.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
“Make completion updates conditional on the current owner when stale workers must not overwrite a rescued job.” [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log
What if a source were missing?
Temporarily leave out one source to see which research targets retain excerpts in this report.
Showing the original excerpt ledger.
According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming rows compared with a normal SELECT?
3 recorded excerpts remain.
Inspect remaining excerpts
“FOR UPDATE waits when another transaction already owns the row lock.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
“Add SKIP LOCKED, and PostgreSQL omits rows that cannot be locked immediately.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
“Several workers can therefore claim different jobs without coordinating through application code.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
According to https://www.postgresql.org/docs/current/sql-select.html, what inconsistent-view caveat applies to FOR UPDATE SKIP LOCKED or to locking clauses in SELECT?
3 recorded excerpts remain.
Inspect remaining excerpts
“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“The result is intentionally inconsistent.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
“PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads?
2 recorded excerpts remain.
Inspect remaining excerpts
“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
Which crash and idempotency questions for claiming jobs with FOR UPDATE SKIP LOCKED versus a normal SELECT are not resolved by https://www.postgresql.org/docs/current/sql-select.html?
4 recorded excerpts remain.
Inspect remaining excerpts
“A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“This is the important turn: claiming exactly once is not the same as producing a side effect exactly once.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
“Make completion updates conditional on the current owner when stale workers must not overwrite a rescued job.”
S2 · hch-log.com · PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log · version ee20e3142cad64b9bd986c61f058f635918e5bae2934a80b7efce59589db5bfb
Targets are requested topics, not verified assertions. Excerpts do not prove truth or independent corroboration. This view keeps the answer, confidence and payments unchanged and makes no new requests.
Research evidence matrix
Compare unverified research targets with cited sources and inspect recorded excerpts. An empty cell means no inspectable excerpt was recorded; it does not establish whether a claim is true, false, or disputed. Coverage and agent confidence do not prove entailment, measured accuracy or complete synthesis.
| Research target (unverified) | Inspection status | [S1] Build a PostgreSQL worker queue with SKIP LOCKEDPublication: jpcasabianca.comPublished: Not recorded | [S2] PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-logPublication: hch-log.comPublished: Not recorded |
|---|---|---|---|
| According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming rows compared with a normal SELECT? | Recorded excerpt | No excerpt recorded | Inspect 3 excerptsFOR UPDATE waits when another transaction already owns the row lock. Add SKIP LOCKED, and PostgreSQL omits rows that cannot be locked immediately. Several workers can therefore claim different jobs without coordinating through application code. |
| According to https://www.postgresql.org/docs/current/sql-select.html, what inconsistent-view caveat applies to FOR UPDATE SKIP LOCKED or to locking clauses in SELECT? | Recorded excerpt | Inspect 1 excerptPostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table. | Inspect 2 excerptsThe result is intentionally inconsistent. PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables. |
| According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads? | Recorded excerpt | Inspect 1 excerptPostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table. | Inspect 1 excerptPostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables. |
| Which crash and idempotency questions for claiming jobs with FOR UPDATE SKIP LOCKED versus a normal SELECT are not resolved by https://www.postgresql.org/docs/current/sql-select.html? | Recorded excerpt | Inspect 2 excerptsA worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever. The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery. | Inspect 2 excerptsThis is the important turn: claiming exactly once is not the same as producing a side effect exactly once. Make completion updates conditional on the current owner when stale workers must not overwrite a rescued job. |
Reference export
2 article references. Recorded titles, links and dates; observed scholarly records also include supplied authors, DOI and journal metadata with read limits. Review metadata before using in a paper. Import RIS into Zotero with File → Import.
Cited sources and references
- 1Build a PostgreSQL worker queue with SKIP LOCKEDjpcasabianca.comFree public reference · no creator payment · extracted html text50%
- 2PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-loghch-log.comFree public reference · no creator payment · extracted html text50%
Decision log · 69 steps
Breaking down: "We are considering a PostgreSQL jobs table consumed by three workers. Use https://www.postgresql.org/docs/current/sql-select.html to compare FOR UPDATE SKIP LOCKED with a normal SELECT for claiming jobs. Produce a decision table plus a transaction outline. Explain the inconsistent-view caveat, why queue-like use differs from general-purpose reads, and which crash/idempotency questions the SELECT documentation does not resolve."
Identified 4 research target(s) to investigate; these are not established facts
Deep mode: up to 4 paid/cached/public reads plus one bounded gap-expansion pass when needed.
Web search: 4/4 planned queries attempted, 4 succeeded, 24 public page previews, 0 unavailable queries. Snippets are discovery only. Public reads spend no USDC; model and service operating costs remain separate.
Discovered 0 verified creator source(s) and 24 free public reference(s)
Claim-aware portfolio (exhaustive; bounded selection, not a claim of global optimality) selected 4/15 positive proposal(s): 4 free/cache selections + 0 paid fresh selections, predicting 4/4 claim(s) above the evidence floor with $0.000000/$0.015000 fetch USDC reserved.
Free-preview pre-check maps an actionable source to every sub-claim (4/4); paid reading may proceed within the budget.
Strong topical match on postgresql, table, use, select, update, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 2, 3, 4; 0 fetch USDC, 1 attention slot).
Strong topical match on postgresql, table, docs, select, update, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 2, 3, 4; 0 fetch USDC, 1 attention slot).
Strong topical match on postgresql, table, use, skip, locked, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 2, 3, 4; 0 fetch USDC, 1 attention slot).
Strong topical match on postgresql, select, update, skip, locked, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 2, 3, 4; 0 fetch USDC, 1 attention slot).
Strong topical match on jobs, workers, select, update, skip, addresses sub-claim 1 & 2 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, workers, select, update, skip, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, jobs, select, update, skip, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, jobs, workers, use, select, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, workers, select, update, skip, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, jobs, workers, use, org, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Weak match (only select, update, skip, locked, behave); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Strong topical match on postgresql, table, org, select, update, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, org, current, select, update, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on postgresql, sql, select, update, locked, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Weak match (only workers, update, skip, locked, rows); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Strong topical match on postgresql, sql, select, update, skip, addresses sub-claim 1 & 2 & 3 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Strong topical match on sql, select, update, locked, transaction, addresses sub-claim 1 & 2 & 4; worth the 0 USDC toll. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Weak match (only table, select, update, transaction); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Weak match (only inconsistent); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Weak match (only decision, inconsistent); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Weak match (only inconsistent); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Weak match (only inconsistent); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Weak match (only inconsistent, view, like, purpose); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Weak match (only inconsistent); not worth 0 USDC. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
READ Building a PostgreSQL Job Queue with FOR UPDATE SKIP LOCKED | Akshay Gupta - selected original public page, 0 USDC; not a cache hit.
Public page unavailable (html-extraction-unavailable); no evidence admitted. Continuing research.
READ PostgreSQL Job Queues with SKIP LOCKED | CodeNotes - selected original public page, 0 USDC; not a cache hit.
Public page unavailable (html-extraction-unavailable); no evidence admitted. Continuing research.
READ Build a PostgreSQL worker queue with SKIP LOCKED - selected original public page, 0 USDC; not a cache hit.
Read extracted public text from https://jpcasabianca.com/journal/build-postgres-worker-queue-with-skip-locked/ - S1; quote matching establishes source grounding, not fact verification.
READ PostgreSQL SKIP LOCKED: Job Queue, Not Magic Broker · hch-log - selected original public page, 0 USDC; not a cache hit.
Read extracted public text from https://hch-log.com/en/article/share/postgresql-skip-locked-job-queue/ - S2; quote matching establishes source grounding, not fact verification.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 60% covered by S2 — S2 directly contrasts behavior: a normal SELECT ... FOR UPDATE waits when another transaction owns the row lock, while adding SKIP LOCKED makes PostgreSQL omit rows that cannot be locked immediately, allowing several workers to claim different jobs without application coordination. However, the supplied passages are from hch-log.com, not the requested postgresql.org SELECT documentation, and they do not quote the official wording or details such as locking clause scope, LIMIT/ORDER BY interaction, or exact semantics from the requested page.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 50% covered by S1, S2 — S1 and S2 both state that SKIP LOCKED provides an intentionally inconsistent view unsuitable for general queries but useful for queue-like tables. This captures the caveat at a high level, but the passages are secondary summaries, not the requested postgresql.org SELECT documentation, and they do not explain the official caveat in the documentation's own terms or scope.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 50% covered by S1, S2 — S1 and S2 indicate that the inconsistent view is unsuitable for general queries but useful for multiple consumers accessing a queue-like table, which gives the core distinction. Still, the supplied passages do not come from the requested postgresql.org SELECT documentation and do not elaborate the documentation's rationale beyond the summary phrase.
Sub-claim "Which crash and idempotency questions for claiming jobs with…": 60% covered by S1, S2 — S1 lists crash-after-claim, repeated side effects, leases, idempotent handlers, retry policy, terminal states, and observable recovery; S2 adds at-least-once delivery, idempotency, short transactions, leases, retries, and conditional completion. These passages identify many crash/idempotency questions that the SELECT documentation does not resolve, but they are secondary sources and do not systematically enumerate what the requested postgresql.org SELECT page specifically omits.
Coverage is partial but adequate for the requested comparison and caveat: the gathered sources directly explain normal SELECT FOR UPDATE waiting versus SKIP LOCKED omission, the inconsistent-view caveat, queue-like versus general-purpose use, and many unresolved crash/idempotency concerns. The main gap is that the passages are secondary summaries rather than the requested postgresql.org SELECT documentation itself. No skipped source clearly fills that specific gap, and the remaining budget is only 0.015, so buying more is not justified.
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 80% assessed by S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 80% assessed by S1, S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 80% assessed by S1, S2
Final check — "Which crash and idempotency questions for claiming jobs with…": 50% assessed by S1, S2
Final coverage assessment — The supplied excerpts directly answer the behavioral comparison, the inconsistent-view caveat, and the queue-vs-general-read distinction, but they do not resolve crash/idempotency questions from the SELECT documentation itself. S1 and S2 are secondary sources that paraphrase PostgreSQL documentation; they provide the needed statements but do not supply the primary documentation text. The fourth sub-claim asks which crash/idempotency questions are not resolved by the SELECT documentation; the sources identify several such questions (crash after claim, exactly-once side effects, leases, retries, idempotency, stale workers, poison work), but they do not frame them as an explicit list of what the SELECT documentation fails to resolve. The assessment does not establish a complete supported answer for every requested part.
Synthesizing a grounded answer from 2 source(s)…
Relevance review returned; only checked excerpts can retain support, and review cannot raise it.
Delivering qualified source excerpts; complete synthesis and per-assertion support remain unverified.
Source-matched public excerpt (no creator reward) — S2, research target 1, proposed support 50% (estimate, not entailment): “FOR UPDATE waits when another transaction already owns the row lock.”
Source-matched public excerpt (no creator reward) — S2, research target 1, proposed support 90% (estimate, not entailment): “Add SKIP LOCKED, and PostgreSQL omits rows that cannot be locked immediately.”
Source-matched public excerpt (no creator reward) — S2, research target 1, proposed support 40% (estimate, not entailment): “Several workers can therefore claim different jobs without coordinating through application code.”
Source-matched public excerpt (no creator reward) — S1, research target 2, proposed support 90% (estimate, not entailment): “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessi…”
Source-matched public excerpt (no creator reward) — S2, research target 2, proposed support 60% (estimate, not entailment): “The result is intentionally inconsistent.”
Source-matched public excerpt (no creator reward) — S2, research target 2, proposed support 80% (estimate, not entailment): “PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.”
Source-matched public excerpt (no creator reward) — S1, research target 3, proposed support 70% (estimate, not entailment): “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessi…”
Source-matched public excerpt (no creator reward) — S2, research target 3, proposed support 60% (estimate, not entailment): “PostgreSQL says it is unsuitable for general-purpose queries, but useful for queue-like tables.”
Source-matched public excerpt (no creator reward) — S1, research target 4, proposed support 70% (estimate, not entailment): “A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction…”
Source-matched public excerpt (no creator reward) — S1, research target 4, proposed support 60% (estimate, not entailment): “The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
Source-matched public excerpt (no creator reward) — S2, research target 4, proposed support 70% (estimate, not entailment): “This is the important turn: claiming exactly once is not the same as producing a side effect exactly once.”
Source-matched public excerpt (no creator reward) — S2, research target 4, proposed support 60% (estimate, not entailment): “Make completion updates conditional on the current owner when stale workers must not overwrite a rescued job.”
Prepared source excerpts citing 2 source(s); complete synthesis is unverified
Confidence: Low — Only source excerpts are delivered; complete synthesis and per-assertion support remain unverified. Evidence assessment: the final assessment does not establish a complete supported answer for every requested part.
jpcasabianca.com contributed 50% - free public reference; reward share withheld
hch-log.com contributed 50% - free public reference; reward share withheld
Done. Spent $0 across 0 confirmed/simulated payment(s) to creators.
Portable research receipt
Take the evidence trail with you
One deterministic JSON bundle binds the answer, visible decisions, exact article versions, claim evidence and a Circle-settlement snapshot under SHA-256. Retain the digest to detect later changes; the self-check is not a publisher or Keryx signature.
Carries this dispatch’s question as context — never its answer. The next dispatch is read from sources bought for it.